In this week’s True Grit Nugget, instructor Marc Jonez breaks down the three types of basement fires and how each can create a different flow path. He explains why understanding access, ventilation, and timing is critical before making changes that could impact fire behavior and crews operating inside.

This training took place at the Colorado State Fire Fighters Association 2026 Fire College in Aurora, Colorado.

VIDEO TRANSCRIPTION:

 Types of basement fires. A walkout basement where we have full access to it, and a second one is where we have no access, and then we have a limited window effect. Each one of those are creating a different fire flow effect, and we have to be aware of this. So a 360 on this is really important because it changes how we’re gonna do it.

I almost want to time this perfectly, and this is never gonna happen is timing something perfectly on a fire ground. But we really want to have this planned because I want to know where that, that initial fire attack crew is at. Have they made the stairs or not, right? Because if, if they’re at the top of the stairs and I change the flow path, especially if it’s a vent limited fire, I’m dramatically changing what and how that hits.

What I would say is we need to be, as the fire service, very much aware of those three basement types, how flow paths work in those, and then the timing and run order of those. There are times when honestly our best effect is to do absolutely nothing and go down with the hose line to avoid any kind of dynamic change.

At least it’s predictable that way. It’s predictable based upon if we go in the front door, we know we’re going through it, right? We know the flow path. When we start having uneven flow paths because we opened something up, if we try to reset a fire, once again, what’s the problem with that in particular with a basement fire, right?

If we reset a fire from the outside, we lose any visibility, we’ve banked it down, and our smoke and visibility levels have completely changed in arguably already the hardest fire we’re gonna fight.

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